JPH11112075A - Semiconductor laser device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separately make light absorbing layers naturally, by including a light absorbing face consisting of a main face region and an inclined region which has a different azimuth from the main face and also has a different impurity percentage from the main face, being interposed in an n-side clad layer split in plural layers. SOLUTION: A groove which has an incline where face azimuth is about (411) A is obtained by etching a resist mask in the shape of a line-and-space after formation, and etching a substrate 1 where face azimuth is 6 deg. off from the face (100) to the face (111) A. A part of a clad layer 2 on n side, a light absorbing layer 8 large in the quantity of light absorption, a light absorbing layer 9 small in the quantity of light absorption, a part of the clad layer 2 on n side, an active layer 3, a part of a clad layer 4 on p side, a current narrowing layer 5, and a part of the clad layer 4 on p side are stacked in order. The light absorbing layers 8 and 9 are interposed in the middle of the clad layer 2 on n side. They can be separately made naturally by doping them with Si and Se, which are n-type impurities, at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser device made of an AlGaInP (As) -based mixed crystal having an oscillation wavelength in the 0.6 [μm] band and a method of manufacturing the same.

[0002] A 0.6 [μm] band semiconductor laser has a short wavelength and can be narrowed down to a small spot size.
(Digital Video Disk) high-density and large-capacity storage devices have been realized.

One of the problems that must be solved in order for a 0.6 [μm] band semiconductor laser to be able to maintain high output at high temperatures is the control of the transverse mode. Generally, the transverse mode is controlled. Otherwise, when the temperature or output changes, the transverse mode changes and the laser spot moves, so that, for example, in the above-mentioned storage device, writing errors frequently occur, and normal operation cannot be performed. It becomes possible.

The present invention discloses a means for stably controlling a transverse mode in a semiconductor laser of 0.6 [μm] band.

[0005]

2. Description of the Related Art Generally, in order to improve the confinement of a transverse mode in a semiconductor laser and control the transverse mode stably,
Two means are known: confinement by refractive index difference and confinement by light absorption.

FIG. 5 is a diagram for explaining light confinement caused by the distribution of the refractive index and the distribution of the absorption coefficient.

In the figure, (A) shows a near-field (nearfield) pattern of a laser oscillating in a low-order mode.
(B) shows a near-field profile of a laser oscillating in a low-order mode, (C) shows a refractive index distribution, and (D) shows an absorption coefficient distribution.

In the case where there is a distribution of the refractive index as shown in (C), light is confined in a place where the refractive index is high.
Oscillation is more likely to occur in the lower-order mode shown in (A) than in the higher-order mode shown in (B), and the transverse mode is stabilized.

In the case where there is a distribution of the absorption coefficient as shown in (D), light is confined in a place where absorption is low.
Oscillation is more likely to occur in the lower-order mode shown in (A) than in the higher-order mode shown in (B), and the transverse mode is stabilized.

FIG. 6 is a fragmentary front view showing a typical buried ridge type semiconductor laser having an oscillation wavelength in the 0.6 [μm] band.

In the figure, 1 is a substrate, 2 is an n-side cladding layer, 3 is an active layer, 4 is a p-side cladding layer, 6 is a p-side electrode,
7, an n-side electrode; 14, a current confinement layer; 15, a spike prevention layer; and 16, a contact layer.

In this semiconductor laser, MOVPE (me
talorganic vapor phase epi
The crystal growth by the taxy method is performed three times, and the current confinement layers 14 made of GaAs are buried on both sides of the light emitting portion, and the higher mode is controlled by utilizing the fact that light is absorbed by GaAs. Then, the lateral mode is controlled by the gain waveguide.

However, in manufacturing the semiconductor laser, it is necessary to perform crystal growth three times by the MOVPE method, thereby lowering the manufacturing yield.
Prevents price reductions.

FIG. 7 and FIG. 8 are cutaway front views of a main part showing a slope emitting semiconductor laser developed by the group of the present applicant (Japanese Patent Application Laid-Open No. 6-45708, if necessary).
See).

In the drawing, the same symbols as those used in FIG. 6 represent the same parts or have the same meanings.
Reference numeral 5 denotes a current confinement layer, and 17 denotes an n-side clad layer doped with Se. The arrows shown in FIG. 8 indicate the paths of the electron current.

In this semiconductor laser, since the crystal growth by the MOVPE method can be performed in one step, the production yield is high and the price can be reduced, and the current confinement structure can be reduced by the MOVPE method. In this structure, the current is efficiently injected into the light emitting portion because the light emitting portion is manufactured by utilizing the plane orientation dependency of the impurity doping.

Further, in this semiconductor laser, the transverse mode is mainly confined by the refractive index waveguide, and more specifically, the refractive index in the lateral direction of the sloped light emitting portion generated by bending the active layer. A structure in which low-crystals are located makes it possible to confine light in the lateral direction.

If the lateral mode confinement effect due to the gain waveguide can be added to the lateral mode confinement effect due to the actual refractive index waveguide provided in such a slope emission type semiconductor laser, it can be further compared with the conventional semiconductor laser. Transverse mode control can be stably realized under high temperature and high output.

However, the above described 0.6 [μm]
In a typical buried ridge type semiconductor laser having an oscillation wavelength in a band, a current confinement layer made of GaAs is buried.
Since the MOVPE method is carried out three times, if the same means is employed, the advantages of the high-yield yield and low cost due to the single growth of the MOVPE method, which are the advantages of the slope emission type semiconductor laser, are lost. Would.

[0020]

SUMMARY OF THE INVENTION The present invention relates to a MOVPE
Method, that is, the lateral mode confinement effect due to the gain guiding can be added to the lateral mode confinement effect due to the index guiding while maintaining the advantages of the single growth by the method, that is, the advantages of high manufacturing yield and low cost. An attempt is made to realize more stable transverse mode control.

[0021]

The present invention utilizes the fact that the rate of incorporation of impurities depends on the plane orientation of the semiconductor surface, and absorbs light in the vicinity of the light emitting portion and near both sides of the light emitting portion in the active layer. A structure that can vary in degree is realized.

In general, AlG grown on a GaAs substrate
It is known that in an aInP (As) -based mixed crystal, the incorporation rate of impurities differs depending on the plane orientation at the outermost surface of the crystal during crystal growth by the MOVPE method. , Kondo et al., Journal.
of Applied Physics 76 (199
4) 914 ").

By utilizing this technique, when a crystal is grown in a state where different plane orientations appear on the semiconductor surface,
Semiconductor layers having different impurity concentrations according to the plane orientation can be grown simultaneously.

The absorption of light in the semiconductor depends on the carrier concentration or the deep level density. The higher the carrier concentration or the higher the deep level density, the larger the light absorption tends to be.

FIG. 9 is a diagram for explaining that the light absorption coefficient of a semiconductor depends on the carrier density and the deep level density.

In the figure, (A) shows the light absorption coefficient (vertical axis) for the carrier density (horizontal axis), and (B) shows the light absorption coefficient (vertical axis) for the deep level density (horizontal axis). Are respectively shown.

Since the carrier concentration can be adjusted depending on the concentration of the impurity which causes the shallow level in the crystal, the absorption of light is adjusted according to the plane orientation in a semiconductor crystal having different plane orientations. be able to.

Like the above-mentioned shallow level, the deep level density can be adjusted depending on the concentration of the source impurity (eg, O) in the crystal. Light absorption can be adjusted according to the direction.

According to the above-mentioned fact, in the vicinity of the active layer, a layer having a low impurity concentration near the light emitting portion and a layer having a high impurity concentration on both sides of the light emitting portion are simultaneously grown, whereby the light emitting portion is formed. In addition, the light absorption can be made different between the two sides, and the amount of light absorption depends on the respective plane orientations on the surface of the step-shaped substrate (see FIG. 7) and the amount of impurities doped into the light absorption layer. It can be adjusted by the combination of the type and the flow rate, the energy band gap and the layer thickness of the light absorbing layer.

In the conventional slope emitting semiconductor laser described with reference to FIGS. 7 and 8, Se is used as an n-type impurity for doping the n-side cladding layer. Since the Se concentration of the n-side cladding layer on both sides of the light-emitting portion is higher than that of the n-side cladding layer in the n-side cladding layer, there should be a difference in light absorption between the vicinity of the light-emitting portion and both sides of the light-emitting portion. It is.

However, in this case, since the only impurity doped in the n-side cladding layer is Se, the doping amount of Se is large on both sides of the light emitting portion of the active layer, but is small near the light emitting portion. There is a problem in injecting the carrier.

[0032]

According to the present invention, an impurity which is uniformly doped without depending on the plane orientation at the semiconductor surface and contributes to the conductivity of the semiconductor, and depends on the plane orientation at the semiconductor surface. Simultaneous doping with impurities with different incorporation rates into the crystal, stabilizing the transverse mode by making a difference in light absorption near the light emitting part of the active layer and on both sides of the light emitting part, and adding carriers to the light emitting part of the active layer The basis is to make it easier to inject.

As described above, in the semiconductor laser device and the method of manufacturing the same according to the present invention, (1) an n-side cladding layer (for example, n-side cladding layer 2) having a plurality of divided layers. The light absorbing layer (for example, the light absorbing layer 8) includes a main surface region and a slope region having a different plane orientation from the main surface and a different impurity uptake rate from the main surface.
And 9), or

(2) In the above (1), the active layer (for example, the active layer 3) and the cladding layers (for example, the cladding layers 2 and 4) are made of an AlGaInAsP-based material, or ,

(3) In the above (1) or (2),
The light absorbing layer is doped with a plurality of types of n-type impurities, and at least one of the n-type impurities is an impurity which is incorporated and is uniformly doped without depending on the plane orientation of the semiconductor, and the other impurities are The incorporation rate is characterized by being an impurity doped unevenly depending on the plane orientation of the semiconductor, or

(4) In the above (2), n is added to the light absorbing layer.
Si is also doped as a type impurity with O which is a source of a deep level, or

(5) In the above (3), the impurity to be uniformly doped is Si, and the impurity to be non-uniformly doped is Se.

(6) In the above (3), the uniformly doped impurity is Si and the unevenly doped impurity is S, or

(7) In the above (3), the uniformly doped impurity is Si and the unevenly doped impurity is Te, or

(8) The main surface region and the plane orientation different from the main surface and the impurity incorporation different from the main surface are interposed in the p-side cladding layer (for example, the p-side cladding layer 4) having a plurality of divided layers. Or a light absorbing layer also serving as a current constriction (for example, a semi-insulating light absorbing layer 12 and a light absorbing layer 13 also serving as a current constriction for blocking a current) formed of a sloped region having a refractive index. ,

(9) In the above (8), the active layer and the cladding layer are made of an AlGaInAsP-based material, or

(10) In the above (9), the light absorption layer is doped with Zn as a p-type impurity and O which is a source of a deep level together, or

(11) The semiconductor substrate (for example, the substrate 1) is provided with a slope having a plane orientation (for example, (411) A) different from the main surface (for example, a surface turned off by 6 ° from (100) to (111) A). A step of forming a groove for projection, and forming a part of an n-side cladding layer (for example, n-side cladding layer 2) on a semiconductor substrate having the main surface and the slope, and then forming a main surface region and a main surface. Forming a light absorbing layer (for example, light absorbing layers 8 and 9) composed of inclined regions having different plane orientations and different impurity incorporation rates from the main surface, followed by the remaining n-side cladding layer (n-side cladding layer 2) and Laminating necessary semiconductor layers (for example, the active layer 3, the p-side cladding layer 4, and the current confinement layer 5).
Or

(12) A step of forming a groove for exposing a slope having a plane orientation different from the main surface on the semiconductor substrate, and forming a p-side cladding layer (for example, p-side) on the semiconductor substrate having the main surface and the slope. After a part of the cladding layer 4) is formed by lamination, a light absorption layer (for example, light absorption layer) which also serves as a current confinement composed of a main surface region and a slope region having a different plane orientation from the main surface and having a different impurity uptake rate from the main surface. After forming layers 12 and 13), the remaining p-side cladding layer (p-side cladding layer 4)
And a step of laminating and forming necessary semiconductor layers.

By adopting the above means, a structure in which light absorption at both sides of the light emitting portion is larger than that near the light emitting portion of the active layer can be stably formed with a high yield by MOVPE once. It is possible to add the transverse mode confinement effect due to the gain guide to the transverse mode confinement effect due to the refractive index guide, so that the controllability of the transverse mode is greatly improved, and the semiconductor laser has a high temperature and high output. In addition, the injection of carriers into the light emitting portion of the active layer is not hindered.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cutaway front view of an essential part of a slope emitting semiconductor laser for explaining a first embodiment of the present invention.

In the figure, 1 is a substrate, 2 is an n-side cladding layer, 3 is an active layer, 4 is a p-side cladding layer, 5 is a current confinement layer, 6 is a p-side electrode, 7 is an n-side electrode, 8 Denotes a light absorption layer having a large light absorption amount, and 9 denotes a light absorption layer having a small light absorption amount.

As is clear from the figure, the light absorbing layers 8 and 9
Has a configuration interposed in the n-side cladding layer 2.

The main data of each part in the semiconductor laser is exemplified as follows.

(1) Substrate 1 Material: n-type GaAs (plane orientation: (100) to (11)
1) 6 ° off in direction A) Impurity: Si Impurity concentration: 2 × 10 ¹⁸ [cm ⁻³ ] Thickness: １００100 [μm]

(2) Regarding the n-side cladding layer 2 Material: n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Impurity: Si Impurity concentration: 1 × 10 ¹⁸ [cm ^-3 ] Thickness: 2 μm in total

(3) Active Layer 3 Material: i-Ga _0.5 In _0.5 P Thickness: 0.08 [μm]

(4) P-side cladding layer 4 Material: p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Impurity: Zn Impurity concentration: 1 × 10 ¹⁸ [cm ⁻³ ] Thickness: 2 μm in total

(5) Current Narrowing Layer 5 Material (100) plane (main surface): n- (Al _0.7 Ga _0.3 ) _0.5
In _0.5 P (411) A-plane (slope): p- (Al _0.7 Ga _0.3 )
_0.5 In _0.5 P Impurity: Alternating doping of Zn and Se Impurity concentration (100) plane (main plane): 6 × 10 ¹⁷ [cm ⁻³ ] (411) A plane (slope): 1 × 10 ¹⁸ [cm ⁻³ ] Thickness: 0.3 [μm]

(6) P-side electrode 6 Material: AuZn / Ti / Pt / Au

(7) About n-side electrode 7 Material: AuGe / Ti / Pt / Au

(8) Regarding the light absorption layer 8 on the (100) plane and having a large light absorption amount Material: n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Impurity: Simultaneous doping of Si and Se Impurity concentration : 5 × 10 ¹⁸ [cm ^-3 ] Thickness: 0.2 [μm]

(9) (411) Light Absorbing Layer 9 with Small Light Absorption Amount on A Surface Material: n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Impurity: Simultaneous doping of Si and Se Concentration: 2 × 10 ¹⁸ [cm ^-3 ] Thickness: 0.2 [μm]

Next, steps for manufacturing the semiconductor laser of the first embodiment will be described. (1) A line-and-space resist mask is formed by applying a resist process in a lithography technique, and then a wet etching method using an HF-based solution as an etchant is applied. When the substrate 1 whose plane orientation is off by 6 ° from the (100) plane to the (111) A plane direction is etched, a groove having a slope with a plane orientation of about (411) A is obtained.

(2) By applying the MOVPE method, a part of the n-side cladding layer 2, a light absorbing layer 8 having a large light absorption and a light absorbing layer having a small light absorption are formed on the substrate 1. 9,
Part of n-side cladding layer 2, active layer 3, p-side cladding layer 4
, A current constriction layer 5 and a part of the p-side cladding layer 4 are sequentially laminated.

As is apparent from the figure, the light absorbing layers 8 and 9 are interposed in the course of forming the n-side cladding layer 2, and are naturally generated by simultaneously doping n-type impurities, Si and Se. They are formed at a distance of 0.2 [μm] from the active layer 3.

As described above, the material composition of the light absorbing layers 8 and 9 is (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and at the time of growth, trimethyl aluminum (TMAl: Al (CH _{3 3} )
As a source gas of Ga, triethylgallium (TEGa: Ga (C ₂ H ₅ ) ₃ ) as a source gas of In,
As a gas, trimethylindium (TMIn: In)
(CH ₃ ) ₃ ), phosphine (PH ₃ ) was used as the source gas of P, the V / III ratio was 110, the growth rate was 2.2 [μm / hour], and the n-type impurity was Disilane (Si ₂ H ₆ ) and hydrogen selenide (H ₂ Se) were used as source gases for Si and Se.
The flow rate of Si ₂ H ₆ and H ₂ Se is 1 × 10 ¹⁸ [cm] on the (411) A surface when each impurity is doped alone.
^-3 ].

Among the light absorbing layers grown under the above conditions, the n-type carrier density of the light absorbing layer 9 on the (411) A plane is 2 × 10 ¹⁸ [cm ⁻³ ] (Si: 1 × 10 ¹⁸ (cm- ³ ),
Se: 1 × 10 ¹⁸ [cm ⁻³ ]) and (100)
The n-type carrier density of the light absorbing layer 8 on the surface is 5 × 10
¹⁸ [cm ^-3 ] (Si: 1 × 10 ¹⁸ [cm ^-3 ], Se: 4 × 1
0 ¹⁸ [cm ^-3 ]).

(3) In order to form the p-side electrode 6, a thickness of 100 mm is formed on the surface side by applying a resistance heating evaporation method.
Au / Zn / [Å] / 100 [Å] / 1000 [Å]
An Au film is formed, and an alloying heat treatment is performed in an N ₂ atmosphere at a temperature of 450 ° C. for a time of 5 minutes to form a low-resistance layer, and then the thickness is determined by applying an electron beam evaporation method. Is 1
A Ti / Pt film of 2,000 [Å] / 3000 [Å] is formed, and an Au film having a thickness of 5000 [Å] is formed and completed by applying a resistance heating evaporation method.

In order to form the n-side electrode 7, a thickness of 500 [Å] is applied to the back side by applying a resistance heating evaporation method.
/ 100 [Å] / 3000 [Å] to form an Au / Ge / Au film, and a temperature of 400 [° C.] in an N ₂ atmosphere for 5 hours.
[Minute] alloying heat treatment to obtain a low resistance layer,
By applying the resistance heating evaporation method, the thickness is 5000
[Å] The Au film is formed and completed.

Up, down, down
That is, when a configuration is adopted in which the semiconductor device is attached to the heat sink with the p-side electrode 6 facing down, an insulating film made of SiO ₂ may be provided on the surface so that the semiconductor is not affected by the solder.

In this case, for example, by applying a CVD method, the surface is made of, for example, 3000 [Å] Si.
By forming an O ₂ film and applying a lithography technique, for example, a width of 30 μm corresponding to the light emitting region of the stripe is obtained.
m], an Au / Zn / Au film is formed in the same manner as above while leaving the resist film used as an etching mask, and then patterned by a lift-off method. Similarly, formation of a low resistance layer by alloying heat treatment, and thereafter, Ti / Pt
The formation of the film and the formation of the Au film may be performed.

FIG. 2 is a fragmentary front view showing an oblique emission type semiconductor laser for explaining Embodiment 2 of the present invention. The same symbols as those used in FIG. 1 denote the same parts. Shall represent or have the same meaning.

In the drawing, reference numeral 10 denotes a light absorption layer having a large light absorption amount, and reference numeral 11 denotes a light absorption layer having a small light absorption amount.

As is apparent from the figure, the light absorption layers 10 and 11 have a structure interposed in the n-side cladding layer 2.

The main data relating to the light absorbing layers 10 and 11 in the semiconductor laser according to the second embodiment is exemplified as follows.

(1) Regarding the light absorption layer 10 on the (100) plane and having a large light absorption amount Material: n- (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P Impurity: Simultaneous doping of Si and S Impurity concentration : 9 × 10 ¹⁸ [cm ^-3 ] Thickness: 0.2 [μm]

(2) (411) The light absorption layer 11 having a small light absorption amount on the A plane Material: n- (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P Impurity: Simultaneous doping of Si and S Concentration: 2 × 10 ¹⁸ [cm ^-3 ] Thickness: 0.2 [μm]

Next, the growth of the light absorbing layers 10 and 11 in the semiconductor laser according to the second embodiment will be described.

As is apparent from the figure, the light absorbing layers 10 and 11 are interposed in the course of forming the n-side cladding layer 2 and are naturally generated by co-doping n-type impurities, Si and S. Can be made separately,
They are formed at a distance of 0.2 [μm] from the active layer 3.

As described above, the material composition of the light absorbing layers 10 and 11 is (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P, and the source gas of Si and S, which are n-type impurities during growth, is Si. _{Using 2} H ₆ and hydrogen sulfide (H ₂ S), the flow rate of Si ₂ H ₆ and H ₂ S is 1 × 10 ¹⁸ on the (411) A surface when each impurity is doped alone.
[Cm ^-3 ] was adjusted.

Of the light absorbing layers grown under the above conditions, the n-type carrier density of the light absorbing layer 11 on the (411) A plane is 2 × 10 ¹⁸ [cm ^-3 ] (Si: 1 × 10 ¹⁸ [c
m ⁻³ ], S: 1 × 10 ¹⁸ [cm ⁻³ ]), and (1
00) plane, the n-type carrier density of the light absorbing layer 10 is 9 ×
10 ¹⁸ [cm ^-3 ] (Si: 1 × 10 ¹⁸ [cm ^-3 ], S: 8 ×
10 ¹⁸ [cm ^-3 ]).

In general, when light having the same wavelength is absorbed by a crystal, the light absorption efficiency increases when the energy band gap of the crystal is small. Therefore, as shown in the second embodiment, the energy absorption of the light absorption layer is reduced. If the band gap is smaller than the energy band gap of the cladding layer, the absolute amount of light absorption increases, so the structure of the light absorption layer, that is,
The degree of freedom in designing the layer thickness, the doping amount, and the ratio of the amount of light absorption between the slope portion and the flat portion increases.

FIG. 3 is a cutaway front view showing an oblique emission type semiconductor laser for explaining a third embodiment of the present invention. The same symbols as those used in FIGS. It shall represent the same part or have the same meaning.

In the figure, reference numeral 12 denotes a light absorbing layer which is semi-insulating and has a large amount of light absorption, and 13 denotes a light absorbing layer which has a small amount of light absorption.

As is apparent from the figure, the light absorbing layers 12 and 13 have a structure interposed in the p-side cladding layer 4.

The main data concerning the semi-insulating light absorbing layer 12 and the light absorbing layer 13 in the semiconductor laser of the third embodiment is as follows.

(1) The light absorbing layer 12 on the (100) plane which is semi-insulating and has a large amount of light absorption Material: Semi-insulating (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Impurities: Zn and Simultaneous doping of O which is the origin of deep level Impurity concentration: 1.4 × 10 ¹⁷ [cm ^-3 ] Deep level density: 2 × 10 ¹⁷ [cm ^-3 ] Thickness: 0.3 [μm]

(2) (411) Light Absorbing Layer 13 with Small Light Absorption on A-Plane Material: p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Impurity: Zn and deep level Co-doping with O as the origin Impurity concentration: 1 × 10 ¹⁸ [cm ^-3 ] Thickness: 0.3 [μm]

Next, the growth of the light absorbing layers 12 and 13 in the semiconductor laser according to the third embodiment will be described.

As is apparent from the figure, the light absorbing layers 12 and 13 are interposed in the course of forming the p-side cladding layer 4, and are spontaneously formed by simultaneously doping Zn and O as impurities. They are formed at a distance of 0.2 μm from the active layer 3 and have a layer thickness of 0.3 μm as described above.

Zn has a high incorporation rate in the (411) A plane, and O has a high incorporation rate in the (100) plane. Therefore, the p-type layer is in the (411) A plane, and the half is in the (100) plane. Insulating layers can be grown simultaneously, thus:
The semi-insulating light-absorbing layer 12 has both a function of blocking current and a function of absorbing light to confine the transverse mode.

As described above, the material composition of the light absorbing layers 12 and 13 is (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and the source gas of Zn which is a p-type impurity during growth is (CH ₃ ) ₂ Zn is used, and O ₂ is used as a source gas of O which is a source of a deep level.
The flow rate of (CH ₃ ) ₂ Zn is 1 × 10 ¹⁸ [cm ⁻³ ] on the (411) A plane when Zn is doped alone, and the flow rate of O ₂ is O alone. When the doping was performed, the respective values were adjusted so as to be 2 × 10 ¹⁹ [cm ⁻³ ] on the (100) plane.

In the light absorbing layer grown under the above conditions,
(411) The p-type carrier density in the light absorbing layer 13 on the A-plane is 1 × 10 ¹⁸ [cm ⁻³ ] (Zn: 1 × 10 ¹⁸ [c
m ⁻³ ], O: 2 × 10 ¹⁷ [cm ⁻³ ], deep level density originating from O: 1 × 10 ¹⁵ [cm ⁻³ ]), and the light absorbing layer on the (100) plane 12 has a p-type carrier density of 1.4.
× 10 ¹⁷ [cm ⁻³ ], but the deep level density is 2 × 10 ¹⁷
[Cm ^-3 ], the carrier is trapped at a deep level and becomes semi-insulating (Zn: 1 × 10 ¹⁷ [cm ^-3 ], O: 2 × 10 ³ )
¹⁹ [cm ^-3 ]).

FIG. 4 is a fragmentary front view showing an oblique emission type semiconductor laser for explaining Embodiment 4 of the present invention. The same symbols as those used in FIGS. 1 and 2 are used. It shall represent the same part or have the same meaning.

In the figure, reference numeral 20 denotes a light absorption layer having a large light absorption amount, and reference numeral 21 denotes a light absorption layer having a small light absorption amount.

As is clear from the figure, the light absorbing layers 20 and 21 are formed on the surface of the n-side cladding layer 2 and the active layer 3 is formed thereon. 21 and the active layer 3 are in direct contact.

The main data relating to the light absorbing layers 20 and 21 in the semiconductor laser of the fourth embodiment is as follows.

(1) The light absorbing layer 20 on the (100) plane and having a large light absorption amount Material: n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Impurity: Simultaneous doping of Si and Te Impurity concentration : 1.1 × 10 ¹⁹ [cm ^-3 ] Thickness: 0.1 [μm]

(2) (411) Regarding the light absorbing layer 21 having a small light absorption amount on the A plane Material: n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Impurity: Simultaneous doping of Si and Te Concentration: 2 × 10 ¹⁸ [cm ^-3 ] Thickness: 0.1 [μm]

Next, the formation of the light absorbing layers 20 and 21 in the semiconductor laser of the fourth embodiment will be described.

As is apparent from the figure, the light absorbing layers 20 and 21 are spontaneously formed by simultaneously doping the surface of the n-side cladding layer 2 in contact with the active layer 2 with Si and Te as n-type impurities. Can be divided.

As described above, the material composition of the light absorbing layers 20 and 21 is (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and the source gas of Si and Te, which are n-type impurities during growth, is Si. ₂ H ₆ and H ₂ Te were used, and the flow rates of Si ₂ H ₆ and H ₂ Te were 1 × 1 on the (411) A surface when each impurity was doped alone.
It was adjusted to be 0 ¹⁸ [cm ^-3 ].

Among the light absorbing layers grown under the above conditions, the n-type carrier density of the light absorbing layer 21 on the (411) A plane is 2 × 10 ¹⁸ [cm ⁻³ ] (Si: 1 × 10 ¹⁸ (c
m ⁻³ ], Te: 1 × 10 ¹⁸ [cm ⁻³ ]), and
The n-type carrier density of the light absorbing layer 20 on the (100) plane is 1.1 × 10 ¹⁹ [cm ⁻³ ] (Si: 1 × 10 ¹⁸ [cm ⁻³ ]).
Te: 1 × 10 ¹⁹ [cm ⁻³ ]).

In the structure described as the fourth embodiment, the light absorbing layers 20 and 21 are in contact with the active layer 3 having a large light distribution.
Exists, the light absorption can be more effectively utilized.

[0101]

In the semiconductor laser device and the method of manufacturing the same according to the present invention, the main surface region and the main surface are interposed in the n-side cladding layer or the p-side cladding layer having a plurality of divided layers. Thus, a light absorbing layer formed of a slope region having a different plane orientation and a different impurity incorporation rate from the main surface or a light absorbing layer also serving as current confinement is formed.

By adopting the above structure, a structure in which light absorption at both sides of the light emitting portion is larger than that near the light emitting portion of the active layer can be stably manufactured with a high yield by the MOVPE method once. It is possible to add the transverse mode confinement effect due to the gain guide to the transverse mode confinement effect due to the refractive index guide, so that the controllability of the transverse mode is greatly improved, and the semiconductor laser has a high temperature and high output. In addition, the injection of carriers into the light emitting portion of the active layer is not hindered.

[Brief description of the drawings]

FIG. 1 is a fragmentary front view showing a slope emission type semiconductor laser for explaining a first embodiment of the present invention;

FIG. 2 is a fragmentary front view showing a slope emission type semiconductor laser for explaining a second embodiment of the present invention;

FIG. 3 is a fragmentary front view showing a slope emitting semiconductor laser for describing a third embodiment of the present invention;

FIG. 4 is a fragmentary front view showing a slope emitting semiconductor laser for explaining a fourth embodiment of the present invention;

FIG. 5 is a diagram for explaining light confinement caused by a distribution of a refractive index and a distribution of an absorption coefficient.

FIG. 6 is a fragmentary front view showing a typical buried ridge type semiconductor laser having an oscillation wavelength in the 0.6 [μm] band.

FIG. 7 is a fragmentary front view showing a slope emitting semiconductor laser developed by the group of the present applicant.

FIG. 8 is a fragmentary front view showing a slope emission type semiconductor laser developed by the group of the present applicant.

FIG. 9 is a diagram for explaining that a light absorption coefficient in a semiconductor depends on a carrier density and a deep level density.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 n-side cladding layer 3 active layer 4 p-side cladding layer 5 current confinement layer 6 p-side electrode 7 n-side electrode 8 light absorption layer with large light absorption 9 light absorption layer with small light absorption 10 Light absorption layer with large light absorption amount 11 Light absorption layer with small light absorption amount 12 Light absorption layer with semi-insulating and large light absorption amount 13 Light absorption layer with small light absorption amount

Claims (12)

[Claims] 1. A light absorption comprising a main surface region and a slope region having a different plane orientation from the main surface and having a different impurity uptake rate from the main surface, interposed in an n-side cladding layer having a plurality of divided layers. A semiconductor laser device comprising a layer. 2. The method according to claim 1, wherein the active layer and the cladding layer are made of AlGaInAs.
2. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is made of a P-based material. 3. The light-absorbing layer is doped with a plurality of types of n-type impurities, and at least one of the n-type impurities is an impurity which is taken in uniformly without depending on the plane orientation of the semiconductor. 3. The semiconductor laser device according to claim 1, wherein the other impurity is an impurity which is taken in non-uniformly depending on the plane orientation of the semiconductor. 4. The semiconductor laser device according to claim 2, wherein the light absorption layer is doped with Si as an n-type impurity and O which is a source of a deep level. 5. The semiconductor laser device according to claim 3, wherein the impurity that is uniformly doped is Si, and the impurity that is non-uniformly doped is Se. 6. The semiconductor laser device according to claim 3, wherein the impurity that is uniformly doped is Si, and the impurity that is non-uniformly doped is S. 7. The semiconductor laser device according to claim 3, wherein the impurity which is uniformly doped is Si, and the impurity which is non-uniformly doped is Te. 8. A current confinement comprising a main surface region and a slope region having a different plane orientation from the main surface and an impurity incorporation rate different from the main surface interposed in a p-side cladding layer divided into a plurality of layers. A semiconductor laser device comprising a light absorbing layer also serving as a light emitting device. 9. The method according to claim 1, wherein the active layer and the cladding layer are made of AlGaInAs.
9. The semiconductor laser device according to claim 8, comprising a P-based material. 10. The semiconductor laser device according to claim 9, wherein the light absorbing layer is doped with Zn as a p-type impurity and O which is a source of a deep level. 11. A step of forming a groove for exposing a slope having a plane orientation different from that of a main surface on a semiconductor substrate, and laminating a part of an n-side cladding layer on the semiconductor substrate having the main surface and the slope. After the formation, a light absorbing layer composed of a main surface region and a slope region having a different plane orientation from the main surface and having a different impurity uptake rate from the main surface is formed, and the remaining n is continuously formed.
Forming a side-cladding layer and a necessary semiconductor layer in a laminated manner. 12. A step of forming a groove for exposing a slope having a plane orientation different from that of a main surface on a semiconductor substrate, and laminating a part of a p-side cladding layer on the semiconductor substrate having the main surface and the slope. After the formation, a light absorbing layer also serving as a current confinement is formed by forming a main surface region and a slope region having a different plane orientation from the main surface and having a different impurity uptake rate from the main surface. And a step of laminating and forming various semiconductor layers.